Fluid pump with disposable component

ABSTRACT

A pump having a disposable fluid contacting portion which defines a fluid inlet and outlet and a fluid path there between is presented. The pump includes a drive portion configured to engage the disposable portion to cause fluid to be moved from the fluid inlet to the fluid outlet. The disposable portion is configured to be selectively coupled to the drive portion. The disposable portion includes a driven membrane which forms a portion of the fluid path, and the drive portion includes a drive membrane. The two membranes are vacuum coupled to each other, whereby movement of the drive membrane causes the driven membrane to move, causing fluid to be pumped through the disposable portion. The pump has particular utility in the medical field for moving fluid from a source to a patient. The pump may include features such as an air-trap, bubble detection, fluid flow controls, and pressure detection.

This application is a continuation of U.S. application Ser. No.11/832,612, filed Aug. 1, 2007 and now issued as U.S. Pat. No.8,087,906, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to fluid pumps, especially to medicationdelivery pumps.

BACKGROUND OF THE INVENTION

A wide variety of medication delivery pumps are known. In general, thesepumps are configured to deliver a fluid from a source to a patient underpressure.

In order for the pump to be re-usable, at least the portion of the pumpwhich contacts the fluid must be sterilizable. This is difficult forintegral pumps where the pumping mechanism and fluid path are part of asingle unit. For this reason, pumps have been developed with have are-usable pumping unit which cooperates with a fluid path element. Inthis manner, the fluid path element can be separated from the pumpingunit for sterilization and reuse.

These reusable pumps, however, suffer from a number of drawbacks. First,many designs are highly complex, resulting in high costs of manufactureand maintenance costs, and low reliability. In addition, the pumpsgenerally suffer from one or more design issues which result in lessthan optimum performance. For example, it is desirable for the pump toinclude a flow sensor, and yet such a feature is often inconsistent withthe design of the re-usable pump. Also, these pumps generally haveundesirable compliance. “Compliance” is a measure of the volume per unitpressure change in region between intake and outlet of the pump. Manycommercial pumps suffer significantly due to undesirable complianceresulting in either significant change to average and instantaneous flowwhen varying intake and output pressures are experienced.

For example, one re-usable pump design is represented by the IVAC 500series (550, 570, 580, etc.) linear peristaltic pumps. These pumps usesequentially occluding fingers to peristaltically advance fluid byadvancing an occlusion point from the intake end to the outlet end of asecond of tubing. Compliance of the tubing governs the sensitivity ofaverage flow to intake pressure. The average flow of these pumps isquite insensitive to output pressure. However, flow uniformity isdegraded with increasing output pressure and pump segment compliance.

Other examples of re-usable pumps are the Alaris LVP Module and Asena GPpumps. These are dual chamber pumps using conventional cylindricaltubing together with two active pumping regions and two valves, oneabove the upper region and the second between the upper and lowerpumping region. The net filling volume of the upper pump region definesthe cyclic volume pumped and due to the elasticity of this region,variation of intake pressure affects the actual volume delivery. Thelower pump region delivers fluid while the upper chamber is filling,resulting in smoothing of flow output. If elevated output pressureexists, when the lower occlude opens, fluid moves retrograde into theupper pump region. When the upper occluder opens, this excess volumemoves back into the drip chamber, thus reducing net volume pumped anddisturbing uniformity of flow. A second drawback of dual chamber pumpsis the likelihood of air being entrained within the pumping chambers.When this occurs, not only is the compliance increased, but the netpumping volume is directly diminished.

SUMMARY OF THE INVENTION

One aspect of the invention is a fluid pump and a method of pumping ormoving fluid.

One embodiment of a fluid pump comprises a drive unit and a driven unit.The drive unit comprises a housing, a drive or driving membrane and atleast one drive device configured to move the driving membrane betweenat least a first and a second position. The driven unit is preferablyconfigured as the fluid contacting portion of the pump, and thuscomprises a disposable portion of the pump. The driven unit comprises ahousing, a fluid path leading from a fluid inlet to a fluid outlet, andat least one driven membrane defining at least a portion of the fluidpath.

The driven unit is configured to be selectively coupled to the driveunit so that the driven membrane is coupled to the driving membrane,whereby movement of the driving membrane effectuates movement of thedriven membrane, causing fluid to be pumped through the driven unit fromthe fluid inlet to the fluid outlet. Preferably, the driving and drivenmembranes are vacuum coupled, such as by applying a vacuum source to avacuum path or line extending to the interface of the membranes.

The drive unit includes a drive device configured to move the drivingmembrane. In one embodiment, the driving membrane forms a portion of aboundary of a variable volume fluid chamber. The drive device includes apiston or other member for changing the volume of the chamber. Inanother embodiment, the driving membrane is moved directly, such as a byone or more actuators.

The pump may include fluid flow controls, such as a fluid inlet andfluid outlet valve or control. The pump may also include such featuresas an air trap, bubble detector, pressure sensor(s), and fluid lineconnectors.

One embodiment of a method comprises providing a drive unit anddisposable or driven unit and connecting the driven unit with the driveunit so that a driven membrane of the disposable unit is positionedadjacent a driving membrane of the drive unit. The method furthercomprises vacuum coupling the driven membrane to the driving membraneand moving the driving membrane, whereby the driven membrane is movedtherewith, causing fluid to be pumped through the driven unit from afluid inlet to a fluid outlet.

Further objects, features, and advantages of the present invention overthe prior art will become apparent from the detailed description of thedrawings which follows, when considered with the attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fluid pump in accordance with anembodiment of the invention;

FIG. 2 is a cross-sectional side view of the pump illustrated in FIG. 1,with a disposable portion of the pump separated from a drive portionthereof;

FIG. 3 illustrates the pump of FIG. 2 with the disposable portion of thepump mounted to the drive portion, and the pump in first pumpingcondition;

FIG. 4 illustrates the pump of FIG. 2 in a second pumping condition;

FIG. 5 is a cross-sectional side view of a vacuum coupled fluid pump inaccordance with another embodiment of the invention, showing adisposable portion of the pump separated from a drive portion thereof;

FIG. 6 illustrates the pump of FIG. 5 with the disposable portion of thepump mounted to the drive portion;

FIG. 7A is a bottom view of the disposable portion of the pumpillustrated in FIGS. 5 and 6;

FIG. 7B is a top view of the drive portion of the pump illustrated inFIGS. 5 and 6;

FIG. 8A is a bottom view of a disposable portion of a fluid pump inaccordance with another embodiment of the invention;

FIG. 8B is a top view of the disposable portion illustrated in FIG. 8A;

FIG. 8C is a cross-section of another embodiment of a disposable portionof a fluid pump in accordance with the present invention.

FIG. 9A illustrates a first drive mechanism in accordance with anembodiment of the present invention;

FIG. 9B illustrates a second drive mechanism in accordance with anotherembodiment of the invention; and

FIGS. 9C and 9D illustrate a third drive mechanism in accordance withyet another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth inorder to provide a more thorough description of the present invention.It will be apparent, however, to one skilled in the art, that thepresent invention may be practiced without these specific details. Inother instances, well-known features have not been described in detailso as not to obscure the invention.

In general, the invention comprises a fluid pump. The pump hasparticular utility to the medical field, such as for use in pumpingmedication from a source to a patient. In general, the pump has a first,disposable portion, and a second, drive portion. The disposable portionis preferably configured as the fluid contacting portion and defines afluid inlet and outlet and a fluid path there between. The drive portionis configured to engage the disposable portion to cause fluid to bemoved from the fluid inlet to the fluid outlet. The disposable portionis configured to be selectively coupled to the drive portion. In oneembodiment, the disposable portion and the drive portion are vacuumcoupled.

The invention will first be described with reference to FIGS. 1-3, whichillustrate one embodiment of the invention in a conceptual or basicconfiguration. As illustrated in FIG. 1, a fluid pump 20 preferablycomprises a driven unit or portion 22 and a drive unit or portion 24. Ina preferred embodiment, the driven portion 22 is configured to bedisposable (i.e. used a limited number of times, such as once, inconjunction with the drive portion, and then discarded), and as such isreferred to herein as a disposable unit or portion.

In one embodiment, the disposable portion 22 comprises a housing 26which defines a fluid inlet 28 and a fluid outlet 30. The drive portion24 similarly comprises a housing 32 and at least one drive element 34.In a preferred embodiment, the disposable portion 22 and drive portion24 are configured to be vacuum coupled. As such, the drive portion 24may include a vacuum path 37.

In FIGS. 1-3, the housings 26,32 of the disposable portion 22 and driveportion 24 of the pump 20 are illustrated as being generally cylindricalin shape. As detailed herein, the disposable portion 22 and driveportion 24 may have a variety of configurations.

Referring to FIG. 2, in one embodiment, the disposable portion 22 has atop and a bottom. The bottom is configured to mate with a top of thedrive portion 24 of the pump 20. The disposable portion 22 and driveportion 24 could be configured to mate or connect in other manners orpositions, such as in a side-by-side configuration or where the driveportion 24 is mounted on the disposable portion 22.

A fluid pathway is defined from the fluid inlet 28 to the fluid outlet30 of the disposable portion 22. Preferably, this fluid pathway isdefined by the housing 26. In one embodiment, this fluid pathwaycomprises a pump chamber 36, a fluid inlet pathway 38 leading from thefluid inlet 28 to the pump chamber 36, and a fluid outlet pathway 40leading from the pump chamber 36 to the fluid outlet 30. In oneembodiment, the fluid inlet and outlet pathways 38,40 are passagesthrough the housing 26.

As illustrated, the pump chamber 36 comprises a recessed area of thebottom of the housing 26 of the disposable portion 26. In oneembodiment, the recessed area is generally dome or hemi-spherical inshape (i.e. having a perimeter which is circular in shape, but varyingin diameter along its depth). In addition, the pump 20 comprises a firstor driven membrane 42. In one embodiment, the driven membrane 42 spansor covers the recessed area of the disposable portion 22, thus enclosingthat portion to form the pump chamber 36 or otherwise forming at least aportion of the boundary of the pump chamber 36. As detailed below, thedriven membrane 42 preferably comprises a flexible and resilient memberwhich is configured to move relative to the housing 26 of the disposablemember 22.

The drive element 34 of the drive portion 24 is preferably configured toselective move the driven membrane 42 relative to the housing 26 of thedisposable portion 22, thereby changing the volume of the pump chamber36. In this manner, as detailed below, fluid is pumped from the inlet 28to the outlet 30 of the disposable portion 22.

As detailed herein, the drive element 34 may comprise a wide variety ofelements or mechanisms. As illustrated in FIG. 2, the drive element 34comprises a drive or driving membrane 46 movable in response to movementof a piston 44 which is movably located in a portion of the housing 32of the drive portion 24 of the pump 20. In this configuration, thedriving membrane 46 is fluid driven. In particular, the driving membrane46 is associated with a variable volume fluid chamber 48, and preferablycomprises a boundary portion thereof. The piston 44 also defines atleast a portion of the chamber 48, and in that the piston 44 is moveable(such as between extended and retracted positions), the volume of thechamber 48 may be varied. Preferably, the driving membrane 46 isconnected to the housing 32 of the drive portion 24, such as bypositioning a periphery of the driving membrane 46 between a top portionof the housing 32 and a retainer 50 selectively coupled to the housing32.

Fluid 52 is located between a top of the piston 44 and the drivingmembrane 46. As detailed below, movement of the piston 44 causes thedriving membrane 46 to move in and out (the range of movement may vary,such as depending upon desired flow rate, wherein the movement may bebetween convex, concave and/or neutral or flat positions relative to thehousing), thus moving the driven membrane 42 of the disposable portion22 of the pump 20. As detailed below, one or more mechanisms may beprovided for moving the piston 44.

The driven membrane 42 and driving membrane 46 are configured to movewith one another. In a preferred embodiment, the drive membrane 46 anddriven membrane 46 are coupled to one another. Various means may beutilized for this purpose. Preferably, the means allows the disposableportion 22 of the pump 20 to be selectively connected to, anddisconnected from (such as for connection of another disposable portion)the drive portion 24 of the pump.

In one embodiment, the driven membrane 42 and driving membrane 46 arevacuum coupled. As indicated, a vacuum pathway 37 is provided for thispurpose. The vacuum pathway 37 preferably leads from a vacuum source toa region adjacent the drive membrane 46 (and the driven membrane 42 orthe interface of the driven membrane 42 and driving membrane 46 when thedisposable portion 22 is connected to the drive portion 24 of the pump20). As detailed below, a vacuum applied through the pathway 37preferably vacuum couples the driven membrane 42 and driving membrane46.

A method of pumping in accordance with the invention will now bedescribed with reference to FIGS. 3 and 4. In general, activation of thedrive element 34 causes the volume of the pump chamber 36 to vary, thuscausing fluid to be drawn into the fluid inlet 28 and expelled out thefluid outlet 30. In use, a disposable portion 22 is mounted or connectedto a drive portion 24. A vacuum is then applied to vacuum couple thedriven membrane 42 to the driving membrane 46, such as by connecting thevacuum line 37 to a vacuum source.

Referring to FIG. 4, when the piston 44 is moved downwardly, the volumeof the fluid chamber increases. This draws the driving membrane 46, andthus the driven membrane 42 coupled thereto, downwardly. This increasesthe volume of the pump chamber 36, causing fluid to be drawn through thefluid inlet 28 and along the fluid inlet pathway 38 to the pump chamber36.

As illustrated in FIG. 3, when the piston 44 is moved upwardly, thevolume of the fluid chamber 48 decreases, causing the fluid pressure toincrease, forcing the driving membrane 46 upwardly or outwardly. Thiscauses the driven membrane 42 to move inwardly, thus reducing the volumeof the pump chamber 36. This causes fluid to be displaced from the pumpchamber 36 through the fluid outlet pathway 40 to the fluid outlet 30.In this regard, it is noted that while the pressure of the fluid in thepumping chamber 48 of the drive portion 24 of the pump increases (as aresult of movement of the piston 44 reducing the volume of that chamberwhile the volume of fluid therein remains static), the fluid pressure inthe actual fluid pump chamber 36 may or may not increase, although thevolume of that chamber decreases thus causing fluid to be pumped throughthe pump (for example, the change in fluid pressure in the actual fluidpump chamber may negligible or low when the fluid outflow resistance isrelatively low and the overall fluid flow rate through the pump isrelatively high).

As detailed below, in one embodiment, means may be provided forselectively controlling the flow of fluid through the driven portion 22of the pump. Preferably, this means is configured to prevent theback-flow of fluid from the pump chamber 36 to the fluid inlet 28.

In operation, repeated cycling of the piston 44 effects pumping whichcauses a stream or flow of fluid through the pump 20.

Another embodiment of the invention is illustrated in FIGS. 5 and 6.This embodiment pump 120 similarly comprises a first or disposable unitor portion 122 and a second or drive unit or portion 124. Asillustrated, in this embodiment, a housing 126 of the disposable portion122 is generally hemispherical in shape, having a domed top surface and(except as detailed below) a generally flat bottom surface. A fluidinlet pathway 138 leads from a fluid inlet 128 in the top of the housing126 to the bottom of the housing 126. Likewise, a fluid outlet pathway140 leads from the bottom of the housing 126 to a fluid outlet 130 atthe top of the housing. In one embodiment, the fluid inlet 128 and fluidoutlet 130 are located in the same plane, at opposing sides of thehousing 126.

Once again, a pump chamber 136 is defined at the bottom of thedisposable portion 122 of the pump 120. The pump chamber 136 is, asillustrated, a somewhat hemi-spherical chamber extending into the bottomof the housing 126. A driven membrane 142 extends over the bottom of thehousing 126, thus cooperating with the housing 126 to generally enclosethe pump chamber 136.

The driven membrane 142 preferably comprises a flexible and yetresilient member. In one embodiment, as illustrated, the driven membrane142 is approximately the same size as the bottom of the housing 126 ofthe disposable portion 122 of the pump 120. The driven membrane 142 maythus be generally circular in shape. The membrane 142 may be secured tothe housing 126 by a lock ring 156. Preferably, the lock ring 156 isgenerally ring-shaped, having a central opening 158 corresponding to thefluid chamber 136. The lock ring 156 preferably engages the housing 126such that at least a portion of the periphery of the driven membrane 142is positioned there between.

The drive portion 124 of the pump 120 again comprises a housing 132 anda drive element 134. In one embodiment, the housing 132 is generallycylindrical in shape, having a cylindrical outer wall with a top and abottom. The drive element 134 comprises a drive or driving membrane 146.Means are provided for moving the driving membrane 146. In oneembodiment, this comprises a piston 144 and fluid 150. In the embodimentillustrated, a piston 144 is configured to move up and down relative tothe housing 132 of the drive portion 124, such as within a chamberdefined in an interior area thereof. A variable volume fluid chamber isdefined by the housing 132, the drive membrane 146, and a bellows 160and associated mount.

As illustrated, the bellows 160 is located between a top mount 162 a anda bottom mount 162 b, the bottom mount 162 b being connected to orotherwise configured to move with the piston 144. In one embodiment, thebottom mount 162 b might simply comprise the head of the piston 144 andthe top mount 162 a might comprise a portion of the housing 132. Thebellows 160 comprises an accordion-like expandable and contractablemember, whereby expansion and contraction of the bellows 160 viamovement of the piston 144 causes the volume of the fluid chamber tochange (thus changing the pressure of the fluid therein and the locationof the driving membrane 146).

The pump 120 is configured so that the driving membrane 146 engages thedriven membrane 142. In the embodiment illustrated, where the drivenmembrane 142 is inset from the bottom of the lock ring 156, the drivingmembrane 146 may be located outwardly of the top of the housing 132 ofthe drive portion 124. As illustrated, the housing 132 includes a flangeor mount 164 which extends upwardly from the remainder of the topportion of the housing 132. The driving membrane 146 extends across thismount 164. Preferably, the mount 164 is sized to fit within the opening158 of the lock ring 156 so that: (1) a seal is defined between themount 164 and lock ring 156; and (2) the driving membrane 146 and drivenmembrane 142 engage one another.

As indicated above, means are preferably provided for selectivelycoupling the driving and driven membranes so that they move with oneanother, and yet which allows the disposable portion 122 of the pump 120to be removed from the drive portion 124 in a manner allowing the driveportion 124 to be re-used with another disposable portion 122. In oneembodiment, this means comprises a vacuum seal created by a vacuumdevice or source (not shown) via a vacuum line 137. The vacuum line 137leads from the vacuum device or source to an interface between thedriven membrane 142 and the driving membrane 146. As illustrated, thevacuum line 137 extends through the lock ring 156 (such as comprising apassage formed therein), and leading to the opening 158 therein. Thevacuum line 137 may terminate at a sloping or recessed portion of thelock ring 158 at a point below the driven membrane 142. As detailedbelow, this permits air to be drawn from the space between the drivingmembrane 146 and driven membrane 142, thus vacuum coupling the twomembranes to one another.

Preferably, the pump 120 is configured to control the flow of fluidbetween the fluid inlet pathway 138 and the fluid chamber 136, and thefluid chamber 136 and the fluid outlet pathway 140. In particular, it isdesired that the pump 120 be configured so that when fluid is drawn intothe fluid chamber 136, it is drawn through the fluid inlet pathway 138,and not backwardly through the fluid outlet pathway 140. Likewise, whenfluid is pumped out of the fluid chamber 136, it is preferably deliveredthrough the fluid outlet pathway 140, and not back to the fluid inletthrough the fluid inlet pathway 138.

In one embodiment, one or more valves or other fluid flow controls areprovided for this purpose. As illustrated in FIG. 5, the pump 120includes a fluid inlet valve or control and a fluid outlet valve orcontrol. In a preferred embodiment, the inlet and outlet valves takeadvantage of the driven membrane 142, and in particular, cause utilizethe membrane 142 to selectively open and close fluid paths leading toand from the fluid chamber 136. In the embodiment illustrated, a portionof the driven membrane 142 can selectively be moved so as to open orclose the end of the fluid intake pathway 138 at the bottom of thehousing 126 of the disposable portion 122. Likewise, a portion of thedriven membrane 142 can be moved so as to open or close the end of thefluid outlet pathway 140 at the bottom of the housing 126.

In the embodiment illustrated, a mechanism is provided for selectivelymoving the portions of the driven membrane 142 between the fluid pathwayopening and closing positions. In a preferred embodiment, this mechanismcomprises one or more actuators.

As illustrated, an inlet actuator 168 is configured to move betweenextended and retracted positions (or up and down as illustrated in thefigures), thereby moving the driven membrane 142 up and down in theregion of the fluid inlet pathway 138. As illustrated, the inletactuator 168 is push-rod type element having a nose or end configured toengage the driven membrane 142. In order to permit the inlet actuator168 to engage the driven membrane 142, a passage 172 is located in thelock ring 156 in alignment with the fluid inlet pathway 138.

The inlet actuator 168 is configured to move up and down, such as by adriving mechanism described in more detail below. In a first or upposition, the nose of the inlet actuator 168 presses the driven membrane142 against the bottom of the housing 126 of the disposable portion 122of the pump 120 at the point where the fluid inlet pathway 138intersects the bottom of the housing 126, thereby closing it. At thistime, fluid is generally prevented from flowing between the fluidchamber 136 and the fluid inlet pathway 138.

When the inlet actuator 168 is in a second or down position, the drivenmembrane 142 preferably moves to a position in which it no longer blocksthe fluid inlet pathway 138, as illustrated in FIG. 5. To providesufficient space for downward movement of the driven membrane 142, thetop surface of the lock ring 156 may be recessed at the locationcorresponding to the fluid inlet pathway, as illustrated.

When the fluid inlet pathway 138 is open, a fluid path is preferablydefined between it and the fluid chamber 136. As illustrated, a fluidentry 174 may be defined for this purpose. The fluid entry 174 maycomprise a path or channel defined in the bottom of the housing 126which extends from the fluid chamber 136 to the space above the drivenmembrane 142 in the location of the fluid inlet pathway 138.

The outlet actuator 170 is generally similar to and operates similar tothe inlet actuator 168. As illustrated, the outlet actuator 170 isconfigured to engage the driven membrane 142 in the location of theintersection of the fluid outlet pathway 140 and the bottom of thehousing 126. The outlet actuator 170 extends through a passage 176 inthe lock ring 156. A fluid exit 178, comprising a path or channeldefined in the housing 126, preferably extends from the fluid chamber136 to the space above the driven membrane 142 in the location of thefluid outlet pathway 140.

Preferably, the inlet and outlet actuators 170 are associated with thedrive portion 124 of the pump. A drive mechanism is provided foreffectuating movement of the inlet and outlet actuator 168,170.

FIG. 6 illustrates the pump 120 with the disposable portion 122 mountedto the drive portion 124 for operation. As illustrated, the bottom ofthe lock ring 156 rests upon the top of the drive portion 124. Theflange 164 of the drive portion 124 extends into the opening 158 of thelock ring 156, so that the driving membrane 146 is positioned adjacentthe driven membrane 142. When a vacuum is applied through the vacuumline 137, the driving membrane 146 and driven membrane 142 are vacuumcoupled so that they move in unison.

FIGS. 7A and 7B additionally illustrate the disposable portion 122 anddrive portion 124 of the pump 120. FIG. 7A is a bottom view of thedisposable portion 122 or the pump 120. This figure illustrates thegenerally circular shape of the bottom of the housing 126 thereof, aswell as the dome-shaped pump chamber 136. Further illustrated are thefluid inlet and outlet pathways 138,140. Also illustrated are the fluidentry 174 and fluid exit 178.

FIG. 7B is top view of the housing 132 of the drive portion 124 of thepump 120. This figure further illustrates the inlet actuator 168, outletactuator 170, and driven membrane 146.

Additional aspects of the invention, including a method of pumping, willbe described with reference primarily to FIG. 6. FIG. 6 is an assembledview of the pump 120 detailed above. In particular, as illustrated, thedisposable portion 122 has been connected to or mated with the driveportion 124. At this time, the bottom of the lock ring 156 rests uponthe top of the housing 134 of the drive portion 124. The upwardlyextending flange 164 of the housing 134 extends into the opening 158 inthe lock ring 156, whereby the driving membrane 146 is located adjacentto, or touches, the driven membrane 142.

In operation, a vacuum is applied to the vacuum line 137 to evacuate airfrom the space between the drive and driven membranes 146,142. In thismanner, the two membranes are vacuum coupled and move with one another.A fluid source is connected to the pump 120, such as by connecting afluid line leading from a fluid source to the fluid inlet 128 of thepump 120. Preferably, a similar fluid line is coupled to the fluidoutlet 130 of the pump 120, whereby fluid may be delivered to a desiredlocation, such as a patient.

Fluid is drawn into the pump chamber 136 from the fluid inlet 128 of thepump, through the fluid inlet pathway 138. In order to permit fluid toflow to the chamber, the inlet actuator 168 is moved to a downward orretracted position, thus allowing the driven membrane 142 to move awayfrom the opening of the fluid inlet pathway 138. At that time, fluid mayflow from the fluid inlet pathway 138 through the fluid entry 174 to thepump chamber 136. Inlet fluid flow is induced by downward movement ofthe driven membrane 142, as effectuated by downward movement of thedriving membrane 146 by downward movement of the piston 144.

When fluid is being drawn into the fluid chamber 136, fluid ispreferably prevented from flowing through the fluid exit 178. Inparticular, the outlet actuator 170 is moved to its raised position,forcing the driven membrane 142 over the opening to the fluid outletpathway 140. This prevents fluid from being drawn backwardly through thepump from the fluid outlet 140 towards the fluid chamber 136.

Fluid is forced out of the pump chamber 136 by upward movement of thepiston 144. As the piston 144 moves upwardly, it reduces the volume ofthe variable volume fluid chamber. This increases fluid pressure,forcing the driving membrane 146 upwardly, which in turn forcing thedriven membrane 142 upwardly. This reduces the volume of the pumpchamber 136. Fluid is permitted to flow through the fluid exit 178 byretraction of the outlet actuator 170. At that time, a fluid path isestablished from the fluid exit 178 to the fluid outlet pathway 140 tothe fluid outlet 130 of the pump 120. In order to prevent fluid frombeing delivered backwardly to the fluid inlet 128, inlet actuator 168 ismoved upwardly to close the fluid inlet pathway 138.

This process is then repeated. In particular, the piston 144 beginsmoving downwardly to again increase the volume of the pump chamber 136.The inlet actuator 168 is moved downwardly to permit the flow of fluidfrom the fluid inlet 128 to the pump chamber 136. The outlet actuator170 is moved upwardly to prevent fluid from being drawn backwardly inthe direction of the fluid outlet 130 to the pump chamber 136.

FIGS. 8A and 8B illustrate another embodiment of a disposable unitportion 222 a pump 20. As illustrated, the disposable portion 222 has ahousing 226 having a top 223 a and a bottom 223 b. In use, the bottom223 b of the housing 226 would be placed against or mounted to a drivingor pumping portion or unit, in similar fashion to that detailed above.

As illustrated, the disposable portion 222 again has a fluid inlet 228and fluid outlet 230. In this embodiment, the disposable portion 222defines a bubble trapping chamber 280 (the purpose of which is to catchair in the fluid and prevent it from reaching the pump chamber and beingpumped through the pump) and a pump chamber 236. A fluid inlet pathway238 extends from the fluid inlet 228 to the bubble trapping chamber 280,thereon to the pump chamber 236. A fluid outlet pathway 240 extends fromthe pump chamber 236 to the fluid outlet 230.

In the embodiment illustrated, the housing 226 is generally rectangularin peripheral shape. In one embodiment, various of the fluid pathwaysand/or chambers may be defined by raised or recessed areas. For example,when viewing the bottom of the disposable portion 222 as in FIG. 8A, thepump chamber 236 may appear as a depression in the housing 226. Thisdepression, however, may be defined at least in part by a raised portionextending outwardly from the top of the housing 226, as illustrated inFIG. 8B.

FIG. 8C illustrates yet another embodiment of a disposable unit orportion 322 of a pump in accordance with the present invention. Thisembodiment disposable portion 322 is illustrated conceptually toillustrate various features which the disposable portion 322 mayincorporate.

Once again, this embodiment disposable portion 322 includes a housing326. The housing 326 defines a fluid inlet 328 and a fluid outlet 330.The disposable portion 322 further includes an air trap 380, a bubbledetector 382 and a flow stop 384, as well as the pump chamber 336 (asdefined by the housing 326 and a driven membrane 342 in cooperation withthe housing 326).

As indicated above, the air trap 380 is preferably configured to trapair in the fluid which is drawn into the pump. Air which is trapped inthe air trap 380 may be expelled manually or automatically, such asthrough a port or valve to the exterior of the housing 326 of thedisposable portion 322.

The bubble detector 382 is preferably configured to detect bubbles inthe fluid. The detector 382 is preferably located along an upward fluidoutlet path, to avoid “floating” bubble false alarms. The bubbledetector 382 may comprise a chamber having a reflective side wall andtransmitter/receiver.

In one embodiment, the disposable portion 322 may also comprise a fluidpressure sensor. The sensor may be configured to detect fluid inletand/or outlet pressure.

As indicated above, in various embodiments, one or more drive mechanismsor devices may be provided for moving the various elements of the pump.For example, referring to the embodiment pump 120 illustrated in FIGS. 5and 6, the inlet and outlet actuators 168,170 and the piston 144 may beselectively moved in order to effectuate operation of the pump 120.Various embodiments of drive mechanisms will now be described withreference to FIGS. 9A-9D.

FIG. 9A illustrates a cam-type drive mechanism 434. As illustrated, adrive member 486 is configured to move cam elements corresponding toeach of the members to be driven. In the embodiment illustrated,corresponding to a pump configuration such as that illustrated in FIGS.5 and 6, where there is an inlet actuator 468, an outlet actuator 470,and a piston 444. As illustrated, a first cam member 488 a is associatedwith the inlet actuator 468, a second cam member 488 b is associatedwith the piston 444 (though it could be configured to directly engagethe bellows), and a third cam member 488 c is associated with the outletactuator 470. The cam members 488 a, 488 b, 488 c are configured to bemoved by the drive member 486 in a desired path. As illustrated, eachcam member has a pin which engages a track in the drive member 486. Thepin corresponding to each cam member may be offset from a central axis,whereby the path of the periphery of the cam member is non-circular.Each of the inlet actuator 468, outlet actuator 470 and piston 444 areconfigured to follow those respective paths, whereby they may be movedup and down. Of course, the movement is timed so that, for example, thepump 220 illustrated in FIGS. 5 and 6 operates as described.

Though not shown, one or more drives may be provided for moving thedrive member 486. Such drives may have a variety of configurations andbe powered in a variety of manners, such as mechanically orelectrically.

The drive mechanism is preferably associated with the drive portion ofthe pump of the invention. In one embodiment, the drive mechanism may beconnected to the drive portion, such as an in a manner permitting thedrive mechanism and drive portions to be separated. In anotherembodiment, the drive mechanism is preferably integral with the driveportion, such as being located in a lower portion of the housingthereof.

FIG. 9B illustrates a solenoid drive mechanism 534. As illustrated, afirst drive 588 a in the form of an electrically powered solenoid isprovided. The first drive 588 a preferably moves a drive rod, which inturn drives or moves the inlet actuator 568. Likewise, a third drive 588c is in the form of an electrically powered solenoid. The third drive588 c preferably also includes a drive rod. That drive rod moves theoutlet actuator 570. Lastly, in one embodiment, a second drive 588 b hasthe form of a stepper motor, and is configured to move or drive thepiston 544.

In general, the solenoids comprising the first and third drives 588 a,cmay be configured to move their associated drives between extended andrefracted positions. Preferably, those positions correspond to theextended and retracted positions of the inlet actuator 568 and outletactuator 570.

In a preferred embodiment, the second drive 588 b has the form of alinear stepper motor in order to allow the piston 544 to be moved tovarious positions (such as a retracted and a plurality of extendedpositions between the retracted and a maximum extended position). Inthis manner, the position of the piston 444 may be selectivelycontrolled (such as for controlling the pumping volume and cycle time,as detailed below).

FIGS. 9C and 9D illustrate yet another embodiment of a drive mechanism.In this embodiment, the drive mechanism 634 is configured to directlydrive the drive or driving membrane, rather than drive that membraneindirectly, such as via fluid associated with a variable volume chamber.

As illustrated, this drive mechanism 634 comprises multiple actuators.Preferably, the actuators are nested. In particular, in one embodiment,the drive mechanism 634 comprises a first actuator 590 a, a secondactuator 590 b, and a third actuator 590 c. The first actuator 590 a islocated or housed at least partially within the second actuator 590 b,which in turn is located or housed at least partially within the thirdactuator 590 c.

In one embodiment, the first, second and third actuators 590 a, 590 b,590 c are generally conical in shape, having a first or top end and asecond or bottom end, the first end being smaller in dimension than thesecond end. Preferably, the actuators are sized to permit their relativeand at least partial independent movement, i.e. to permit the firstactuator 590 a to move within the second actuator 590 b, to permit thesecond actuator 590 b to move with respect to the first and thirdactuators 590 a, 590 c, and to permit the third actuator 590 c to moverelative to the second actuator 590 b.

In a preferred embodiment, the actuators can be moved between at leastextended and retracted positions, and preferably one or more positionsthere between. When used with a pump such as that illustrated in FIGS. 5and 6, the extended and retracted positions may correspond to raised orupper, and refracted or lower, positions.

The drive mechanism includes a driving device configured to move theactuators. In one embodiment, each of the actuators defines a passage592 a, 592 b, 592 c through the second or bottom end thereof. A cam-typedrive shaft 594 extends there through. Rotation or other movement of theshaft 594 preferably effectuates movement of the actuators 590 a, 590 b,590 c. In one embodiment, the shaft 594 defines a plurality of camsthereon, at least one cam corresponding to each of the actuators andconfigured to move the corresponding actuator in a specific pattern. Ofcourse, other means might be provided for moving the actuators, such assolenoids, linear stepper motors or other mechanical orelectromechanical drives.

Of course, the drive might have fewer than three or more than threeactuators. Further, the shape of those actuators might vary. Preferably,however, each actuator is configured to engage and move a portion of thedrive membrane.

A particular advantage of this embodiment drive mechanism is thatmovement of the drive membrane is effected without the need for avariable volume chamber or fluid. Instead, movement of the membrane iseffected directly.

In addition, an advantage of multiple actuators is that the amount offorce applied to the drive membrane may be closely controlled bycontrolling how many of the actuators are moved and the extent of theirmovement. In this manner, movement of the driven membrane may be closelycontrolled, thus allowing the fluid flow characteristics to be carefullycontrolled. In addition, the actuators 590 a, 590 b, 590 c mayselectively be moved in the forward or reverse (up or down) directions,again allowing significant control over pumping.

The pump and method of pumping or moving fluid may have numerous otherembodiments in accordance with the invention.

In one embodiment, the pump of the invention has two main portions: afluid contacting portion, which is referred to herein as a disposableunit or portion, and a drive portion. However, the pump may have morethan two portions. For example, the pump may have three portions, suchas a disposable fluid-contacting portion, an actuating portion (such asincluding the inlet actuator, outlet actuator and piston), and a driveportion (such as containing solenoids and stepper motors or a cam driveor the like).

Preferably, the drive portion of the pump is computer controlled,whereby the displaced volume of the pump chamber may be controlled. Forexample, a computer may be utilized to control the multiple actuators590 a, 590 b, 590 c of the embodiment pump illustrated in FIG. 9D or thestepper motor 588 b illustrated in FIG. 9B, whereby the change in volumeof the pump chamber of the pump may be varied over time in a controlledmanner.

The pump may be constructed from a variety of materials and in a varietyof manners. In a preferred embodiment, the disposable portion isconstructed to be disposable, i.e. preferably to have a low cost. Forexample, the disposable may be constructed of a thermo-plastic materialand, as detailed herein, have a simple configuration (such as the solemoving part comprising the driven membrane).

As indicated herein, the pump may be configured to include a number offeatures, such as an air trap, a bubble sensor, a flow rate sensor, oneor more pressure sensors, a flow stop, or combinations thereof. Theconfigurations of these features may vary. For example, various types ofpressure sensors may be utilized as part of the pump. Such sensors maybe utilized, for example, to measure intake, outlet and, in the case offluid actuator, the fluid pressure. In the latter case, the intake andoutput pressures may be inferred from the fluid actuator pressure,eliminating the need for secondary sensors. In one embodiment, the pumpmay include a vacuum pressure sensor. Such a sensor may be utilized todetect or determine the pressure within the vacuum line(s). The sensorcould be associated with or comprise a switch, such as coupled to thevacuum source, for causing the source to be activated when the pump isturned on and/or to be activated in the event vacuum pressure fallsbelow a minimum level.

As indicated above, various drive devices or mechanisms may be utilizedto actuate the pump. Various embodiments have been described andillustrated herein, but others are possible.

The portions of the pump, such as the housings of the disposable portionand drive portion, may have a variety of shapes and sizes. The shapesand sizes of the portions may vary depending on various design criteria.

In a preferred embodiment, the pump includes fluid flow controls tocontrol the flow of fluid there through. As indicated, the fluid flowcontrols may comprise one or more actuated valves. Other types of fluidflow controls than specifically illustrated herein might be utilized.For example, the actuators might be configured to extend directly intoand out of inlet and outlet fluid paths to selectively obscure them.

In a preferred embodiment, the disposable portion of the pump has asingle driven membrane. This single membrane is used as a pump memberand as a valving member for the intake and outlet fluid paths. Thedisposable portion might utilize more than one membrane, however, suchas a first membrane at the pump chamber, a second in conjunction withthe fluid inlet path for serving as the inlet control valve, and a thirdin conjunction with the fluid outlet path for serving as the outletcontrol valve.

In one embodiment, the driven membrane may be separated from thedisposable portion. In this embodiment, after the disposable portion isused, the driven membrane might be thrown away and the remainder of thedisposable portion might be sterilized for reuse. After sterilization, anew driven membrane would be associated with the disposable portion.

In one embodiment, the driving membrane is moved by fluid. As describedabove and illustrated herein, movement of a piston may change the volumeof a chamber containing fluid, which chamber is bounded in at least onearea by the driving membrane. In one embodiment, such as illustrated inFIG. 1, the piston itself may bound a portion of the chamber, wherebymovement of the piston directly changes the volume of the chamber. Inanother embodiment, as illustrated in FIG. 4, the piston may move aboundary of the chamber. In that embodiment, the piston moves a portionof the chamber bounded by a bellows. Of course, the driving membranemight be moved in other manners. For example, fluid might be pumped intothe chamber or be released from the chamber to change the fluid volumetherein. The driving membrane may also be moved directly.

In the preferred embodiment, the driving and driven membranes compriserelatively thin, flexible members. The material from which the membranesare constructed may vary. Further, the membranes may have forms otherthan generally constant thickness material bodies, but may compriseother members which are sufficient resilient to move up and down inresponse to applied forces.

In one embodiment, the disposable portion might be configured withintegral external fluid lines or fluid connectors for mating withexternal devices (such as a fluid source or line).

In one embodiment, the driving membrane is indirectly driven, such as byfluid located in a variable volume chamber. In other embodiments,however, the driving membrane may be directly driven.

In one embodiment, the air trap is configured with a sensor to detect ordetermine when a predetermined amount (such as a maximum amount) of airis contained therein. When such a level or amount of air is sensed, theair may be expelled from the air trap, such as back to a fluid sourcedrip chamber. This may be accomplished by operation of a solenoid orlinear actuator, preferably while the inlet valve is closed to avoid anyinterruption of fluid flow to the patient.

Various aspects of the invention will now be appreciated. First, oneaspect of the invention is a fluid pump having at least two portions, aportion which is configured to contact the fluid to be pumped, andanother portion. Preferably, the pump has a first portion comprising thepumping or drive portion, and a second fluid contacting portion whichcan be selectively connected to or disconnected from the drive portion.Advantageously, this allows the fluid-contacting portion to be disposedof after use, or sterilized after use, while the remaining portion ofthe pump, such as the pumping portion, can be re-used with a newfluid-contacting portion or a sterilized fluid-contacting portion of thepump.

In one embodiment, the fluid-contacting portion of the pump isconfigured to be “disposable.” In particular, the design of that portionof the pump is configured to be simple, whereby it may be relativelyinexpensive to manufacture. This allows that portion to be cheaplyreplaced (avoiding the costs and steps associated with having tosterilize for reuse). In one embodiment, the disposable may beconstructed at least partly of a plastic material for this purpose, suchas in a molding process.

Another aspect of the invention is a multi-piece pump where pumping isfacilitated through the use of one or more engaging membranes ordiaphragms or other flexible members. Preferably, these members areconfigured to move in unison via a vacuum coupling. The vacuum couplinghas the advantage that it is a simple and inexpensive couplingconfiguration. For example, such a configuration avoids the need forcomplex mechanical connections of elements as is common in pump drives.In addition, the vacuum coupling provides a simple way of disconnectingthe pump portions, in that there is no need to disconnect particularlinkages or elements.

Advantageously, the pump of the invention can be configured to be highlycompliant. Further, fluid flow rates or volumes, and pressure, may bevery closely controlled using the pump of the invention.

A significant benefit of the pump of the invention is the highly elasticmembrane of the disposable portion of the pump. This feature minimizesthe dimensional accuracy required of the disposable portion, thusreducing significantly the complexity and cost of manufacture, and thusultimate cost of the disposable portion.

A significant benefit of the vacuum coupling is that the couplingenables the pump to pump against negative output pressures and to aspirefluid from containers lower than the pump (functions which would nototherwise be possible—i.e. the advantages of the disposable portiondetailed above are realized or enabled by the vacuum coupling).

Another feature and advantage of the invention is a pre-pump chamberwhich assists in trapping and eliminating air bubbles which may form inthe fluid itself or travel into to the pump from the fluid source.

It will be understood that the above described arrangements of apparatusand the method there from are merely illustrative of applications of theprinciples of this invention and many other embodiments andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the claims.

1. A fluid pump comprising: a drive unit comprising a housing and aplurality of actuators each configured to move between at least arespective first and a respective second position, wherein the pluralityof actuators are coaxially nested and are generally conical in shapewith first ends and second ends that are larger in dimension than thefirst ends, wherein a first actuator of the plurality of actuators is atleast partially within a second actuator of the plurality of actuatorsand the first end of the first actuator is smaller in dimension that thefirst end of the second actuator; and a driven unit comprising ahousing, a fluid path leading from a fluid inlet to a fluid outlet, andat least one driven membrane defining a portion of the fluid path, thedriven unit configured to be selectively coupled to the drive unit sothat a portion of the driven membrane is coupled to each of theplurality of actuators, whereby movement of at least one of theplurality of actuators effectuates movement of the driven membrane,causing fluid to be pumped through the driven unit from the fluid inletto the fluid outlet, wherein the first ends of the plurality ofactuators are proximate to the driven unit.
 2. The fluid pump of claim1, wherein the first ends of the plurality of actuators aresubstantially circular in shape.
 3. The fluid pump of claim 1, whereinthe plurality of actuators are configured to permit at least partiallyindependent movement of each of the plurality of actuators.
 4. The fluidpump of claim 1, wherein: the plurality of actuators each comprise apassage; the drive unit further comprises a drive shaft comprising aplurality of cams coupled to a shaft; the drive shaft is disposedthrough the passages of the plurality of actuators such that at leastone of the plurality of cams corresponds to each of the plurality ofactuators and is configured to move the corresponding one of theplurality of actuators in a specific pattern; and rotation of the driveshaft effectuates movement of the plurality of actuators.
 5. The fluidpump of claim 1, further comprising a plurality of solenoids whereineach of the plurality of solenoids is configured to move at least one ofthe plurality of actuators.
 6. The fluid pump of claim 1, furthercomprising a plurality of linear stepper motors wherein each of theplurality of stepper motors is configured to move at least one of theplurality of actuators.
 7. The fluid pump of claim 1, further comprisinga plurality of electro-mechanical drives wherein each of the pluralityof drives is configured to move at least one of the plurality ofactuators.
 8. A method of pumping fluid, the method comprising the stepsof: coupling a driven unit between a fluid source and a destination, thedriven unit comprising a housing, a fluid path leading from a fluidinlet coupled to the fluid source to a fluid outlet coupled to thedestination, and at least one driven membrane defining a portion of thefluid path; coupling a drive unit to the driven unit, the drive unitcomprising a housing and a plurality of actuators each configured tomove between at least a respective first and a respective secondposition, wherein the plurality of actuators are coaxially nested andgenerally conical in shape with first ends proximate to the driven unitand second ends that are larger in dimension than the respective firstends, wherein a first actuator of the plurality of actuators is at leastpartially within a second actuator of the plurality of actuators and thefirst end of the first actuator is smaller in dimension that the firstend of the second actuator, the drive unit and driven unit configuredsuch that a portion of the driven membrane is coupled to each of theplurality of actuators; and moving at least one of the plurality ofactuators between the respective first position and the respectivesecond position, thereby moving the driven membrane, thereby causingfluid to be pumped through the driven unit from the fluid source to thedestination.
 9. The method of claim 8, wherein the first ends of theplurality of actuators are generally circular in shape.
 10. The methodof claim 8, wherein the plurality of actuators are configured to permitat least partially independent movement of each of the plurality ofactuators.
 11. The method of claim 8, wherein the step of moving atleast one of the plurality of actuators comprises rotating a drive shaftcomprising a plurality of cams coupled to a shaft, wherein the driveshaft is disposed through a passage of each of the plurality ofactuators such that at least one of the plurality of cams corresponds toeach of the plurality of actuators and is configured to move thecorresponding one of the plurality of actuators in a defined pattern.12. The method of claim 8, wherein the step of moving at least one ofthe plurality of actuators comprises moving at least one of a pluralityof solenoids wherein each of the plurality of solenoids is coupled to atleast one of the plurality of actuators.
 13. The method of claim 8,further comprising moving at least one of a plurality of linear steppermotors wherein each of the plurality of stepper motors is coupled to atleast one of the plurality of actuators.
 14. The method of claim 8,further comprising moving at least one of a plurality ofelectro-mechanical drives wherein each of the plurality of drives iscoupled to at least one of the plurality of actuators.